Permanent magnets are used for products in a wide field including rotary electrical machines such as a motor and a power generator, electrical apparatuses such as a speaker and a measuring device, and vehicles such as an automobile and a railroad vehicle. In recent years, reduction in size of the above-described products has been demanded, and high-performance permanent magnets with high magnetization and high coercive force have been desired.
As examples of high-performance permanent magnets, there can be cited rare-earth magnets such as Sm—Co based magnets and Nd—Fe—B based magnets, for example. In these magnets, Fe and Co contribute to increase in saturation magnetization. Further, these magnets contain rare-earth elements such as Nd and Sm, which brings about a large magnetic anisotropy which is derived from a behavior of 4f electrons of the rare-earth elements in a crystal field. Consequently, it is possible to obtain a large coercive force.